An air vehicle includes a high-lift device provided in a main wing. The high-lift device is stowed in the main wing during cruising and deployed with respect to the main wing during takeoff and landing. The high-lift device is an aerodynamic device for ensuring a lift (aerodynamic lift) during low-speed flight, and therefore is designed so that an emphasis is put on aerodynamic characteristics.
In recent years, demands for reduction of noise radiated from an air vehicle during takeoff and landing have been increasing. Under the circumstances, a high-lift device is regarded as one of major noise sources, particularly during landing. Accordingly, there has been proposed a high-lift device intended to reduce aerodynamic noise. For example, Patent Literature 1 discloses a noise reduction device configured to blow air through slots which are open in the top surface, side surface, and bottom surface of the main wing.